DHT11 -积分数据与十进制数据的差异

Question

我在我的arduino uno中使用DHT11传感器。传感器发送的数据格式为:8位积分RH数据+8位十进制RH数据+8位积分T数据+8位十进制T数据+8位校验和。

我使用的代码是：

//KY015 DHT11 Temperature and humidity sensor 
   int DHpin = 8;
   byte dat [5];
   byte read_data () {
   byte data;
  for (int i = 0; i < 8; i ++) {
if (digitalRead (DHpin) == LOW) {
  while (digitalRead (DHpin) == LOW); // wait for 50us
  delayMicroseconds (30); // determine the duration of the high level to determine the data is '0 'or '1'
  if (digitalRead (DHpin) == HIGH)
    data |= (1 << (7-i)); // high front and low in the post
  while (digitalRead (DHpin) == HIGH); // data '1 ', wait for the next one receiver
 }
  }
   return data;
  }

  void start_test () {
    digitalWrite (DHpin, LOW); // bus down, send start signal
    delay (30); // delay greater than 18ms, so DHT11 start signal can be detected

    digitalWrite (DHpin, HIGH);
    delayMicroseconds (40); // Wait for DHT11 response

    pinMode (DHpin, INPUT);
    while (digitalRead (DHpin) == HIGH);
    delayMicroseconds (80); // DHT11 response, pulled the bus 80us
    if (digitalRead (DHpin) == LOW);
    delayMicroseconds (80); // DHT11 80us after the bus pulled to start sending data

    for (int i = 0; i < 4; i ++) // receive temperature and humidity data, the parity bit is not considered
dat[i] = read_data ();

    pinMode (DHpin, OUTPUT);
    digitalWrite (DHpin, HIGH); // send data once after releasing the bus, wait for the host to open the next Start signal
  }

  void setup () {
    Serial.begin (9600);
    pinMode (DHpin, OUTPUT);
  }

  void loop () {
    start_test ();
    Serial.print ("Current humdity =");
    Serial.print (dat [0], DEC); // display the humidity-bit integer;
    Serial.print ('.');
    Serial.print (dat [1], DEC); // display the humidity decimal places;
    Serial.println ('%');
    Serial.print ("Current temperature =");
    Serial.print (dat [2], DEC); // display the temperature of integer bits;
    Serial.print ('.');
    Serial.print (dat [3], DEC); // display the temperature of decimal places;
    Serial.println ('C');
    delay (700);
  }

这段代码可能不会是我的最后一段代码，但我正在试图了解传感器的数据是怎么回事。我不明白为什么整数数据和十进制数据都被打印为DEC，我也不明白为什么会有“。就在那儿。此代码取自传感器的wiki页面。此外，我总是在湿度和温度的数据部分得到0。

Answer 1

数据转换就像湿度一样，

Humidity Value = ((float)((integral RH data << 8) + 8bit decimal RH data)/(float)10.0)

对于温度来说，

Temperature Value = ((float)((8bit integral T data << 8) + 8bit decimal T data)/(float)10.0)

例如：

8bit integral T data = 0x01 and  8bit decimal T data = 0x32

The real measured temperature value  = ((0x01 << 8) + 0x32) /10
                                     =  (256 + 50 )/10 = 30.6 degree c 

同样的方法，湿度也将用%来表示。请注意，我对DHT22的步骤大小(分辨率为.1度数)对于DHT11，它似乎是1度。

引用您的代码

Serial.print ("Current humdity =");
Serial.print (dat [0], DEC); // display the humidity-bit integer;
Serial.print ('.');
Serial.print (dat [1], DEC); // display the humidity decimal places;
Serial.println ('%');
Serial.print ("Current temperature =");
Serial.print (dat [2], DEC); // display the temperature of integer bits;
Serial.print ('.');
Serial.print (dat [3], DEC); // display the temperature of decimal places;
Serial.println ('C');

由于缺少转换，我认为它不会显示正确的值。